全文获取类型
收费全文 | 364篇 |
免费 | 13篇 |
国内免费 | 1篇 |
专业分类
测绘学 | 7篇 |
大气科学 | 51篇 |
地球物理 | 98篇 |
地质学 | 101篇 |
海洋学 | 48篇 |
天文学 | 41篇 |
综合类 | 1篇 |
自然地理 | 31篇 |
出版年
2021年 | 3篇 |
2020年 | 12篇 |
2019年 | 8篇 |
2018年 | 7篇 |
2017年 | 7篇 |
2016年 | 7篇 |
2015年 | 10篇 |
2014年 | 7篇 |
2013年 | 18篇 |
2012年 | 14篇 |
2011年 | 16篇 |
2010年 | 15篇 |
2009年 | 20篇 |
2008年 | 15篇 |
2007年 | 15篇 |
2006年 | 23篇 |
2005年 | 16篇 |
2004年 | 12篇 |
2003年 | 16篇 |
2002年 | 16篇 |
2001年 | 11篇 |
2000年 | 6篇 |
1999年 | 8篇 |
1998年 | 6篇 |
1997年 | 5篇 |
1996年 | 3篇 |
1995年 | 6篇 |
1994年 | 7篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1989年 | 4篇 |
1987年 | 4篇 |
1986年 | 2篇 |
1985年 | 6篇 |
1984年 | 2篇 |
1983年 | 10篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1979年 | 4篇 |
1977年 | 4篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1973年 | 5篇 |
1971年 | 1篇 |
1970年 | 2篇 |
1969年 | 1篇 |
1967年 | 2篇 |
1962年 | 1篇 |
1900年 | 1篇 |
排序方式: 共有378条查询结果,搜索用时 15 毫秒
21.
In this paper we analyze some Viking infrared thermal mapping (IRTM) measurements of local Martian dust storms observed in the southern tropical region of the planet between Ls=225 and 262°. The derived opacities of these storms show that in the most opaque regions of the cloud, the optical thickness may be ≈6. Away from the individual clouds, the opacity is ≈2, which is still about four times the background level of dustiness in the Martian atmosphere. We find considerable structure in the derived opacity which will create corresponding variations in the atmospheric heating, which in turn may have an important feedback upon the local winds. 相似文献
22.
Comprehensive distribution patterns of physical and chemical characteristics have been obtained from a series of cruises in Liverpool Bay. The marked feature of these distributions was their temporal variability, suggesting that the surface residual circulation is also temporally variable. The influence of wind stress upon the circulation pattern and hence water quality of this sea area is illustrated. 相似文献
23.
Ecohydrology--why hydrologists should care 总被引:1,自引:0,他引:1
24.
25.
B. G. Hunt 《Climate Dynamics》2006,27(7-8):677-694
The CSIRO Mark 2 coupled global climatic model has been used to generate a 10,000-year simulation for ‘present’ climatic conditions. The model output has been analysed to identify sustained climatic fluctuations, such as those attributed to the Medieval Warm Period (MWP) and the Little Ice Age (LIA). Since no external forcing was permitted during the model run all such fluctuations are attributed to naturally occurring climatic variability associated with the nonlinear processes inherent in the climatic system. Comparison of simulated climatic time series for different geographical locations highlighted the lack of synchronicity between these series. The model was found to be able to simulate climatic extremes for selected observations for century timescales, as well as identifying the associated spatial characteristics. Other examples of time series simulated by the model for the USA and eastern Russia had similar characteristics to those attributed to the MWP and the LIA, but smaller amplitudes, and clearly defined spatial patterns. A search for the frequency of occurrence of specified surface temperature anomalies, defined via duration and mean value, revealed that these were primarily confined to polar regions and northern latitudes of Europe, Asia and North America. Over the majority of the oceans and southern hemisphere such climatic fluctuations could not be sustained, for reasons explained in the paper. Similarly, sustained sea–ice anomalies were mainly confined to the northern hemisphere. An examination of mechanisms associated with the sustained climatic fluctuations failed to identify a role for the North Atlantic Oscillation, the El Niño-Southern Oscillation or the Pacific Decadal Oscillation. It was therefore concluded that these fluctuations were generated by stochastic processes intrinsic to the nonlinear climatic system. While a number of characteristics of the MWP and the LIA could have been partially caused by natural processes within the climatic system, the inability of the model to reproduce the observed hemispheric mean temperature anomalies associated with these events indicates that external forcing must have been involved. Essentially the unforced climatic system is unable to sustain the generation of long-term climatic anomalies. 相似文献
26.
We report single-grain quartz luminescence ages for the Puritjarra rock shelter, with the aim of resolving an apparent discrepancy between ages obtained by 14C and a variety of luminescence methods, previously reported. Ages now found at all depths to 75 cm (ages to 30 ka) can be interpreted as largely resolving the differences. This implied caveat arises because single-grain methods are statistically inefficient. As a consequence, a degree of interpretation is inevitable in analysing the data. The emphasis in the present paper is an analysis making use of weighted histograms. The measurements by single grain OSL and 14C, including ABOX–SC, taken together, can be regarded as compatible. They indicate human occupation of the Puritjarra rock shelter at least as early as 30 ka BP. 相似文献
27.
28.
29.
30.